I think i understand it. It appears to be one of those capacitance type things mentioned earlier (like touchlamps). Im not sure if this would work well in my situation. The control circuit will be inside and the sensors will be outside so there will be a fairly long wire between them, im not sure if that would affect it at all because ive never tried anything like that before.

My prefered method is using the water to conduct between 2 wires but ill get some of those resistors so i always have that method as a backup.